The following settings apply to optional overlay layers with ID 1 through 16.
• Layer ID – Identifies the layer ID.
• Video Format – Specifies the video format per layer. Possible formats are RGB, YUV 4:4:4, YUV 4:2:2, or YUV 4:2:0, RGBA, and YUVA444 in case the layer interface type is streaming, and RGBX8, BGRX8, YUVX8, RGBA8, BGRA8, YUVA8, YUYV8, UYVY8, RGBX10, YUVX10, RGB565, Y_UV8, and Y_UV8_420, RGB8, BGR8, YUV8,Y_UV10, Y_UV10_420, Y8, Y10, otherwise.
Note: The video format is chosen at build time and cannot be changed at run-time.
• Enable Global Alpha – When selected, this enables alpha blending for this layer with the layer underneath. The alpha value needs to be programmed at run-time through the AXI4-Lite control interface.
Note: If any of the per pixel alpha formats are selected for a layer, then the global alpha is automatically enabled.
• Enable Scaling – When selected, this enables scaling for this layer. The scale factor (1x, 2x, or 4x) needs to be programmed at run-time through the AXI4-Lite control interface.
• Line Buffer Width – This is only enabled when scaling is enabled for a layer and specifies the maximum width of this layer before scaling. A line buffer with this dimension is allocated in the block RAM to allow for scaling through line repeat. The width needs to be a multiple of the samples per clock setting.
Note: The maximum supported value for LineBuffer width is upto 4096. By default, the set value is 1920. If scaling is enabled, LineBuffer width * scaling factor <= Min (4096, Max Number of Columns)
• Interface Type – Determines whether a layer is either a memory layer or a streaming layer. A memory layer has a memory mapped AXI4 interface while a streaming layer has an AXI4-Stream interface.